Discussion
In frequency shift keying :
(a) The combined signal in FSK modulator generated from two separate oscillators cannot have discontinuities in amplitude.
(b) The combined signal in FSK modulator generated from two separate oscillators cannot have discontinuities in phase.
(c) The combined signal in FSK modulator generated from single oscillator method can have discontinuities in amplitude.
(d) The combined signal in FSK modulator generated from single oscillator method cannot have discontinuities in amplitude.
Answer: C
Only statement (d) is true, so the answer is (d) only.
When the FSK signal is made by switching between two independent oscillators, the two sine waves are not in step at the instant of switching, so the combined waveform jumps in value there: it has a discontinuity in phase, and in general in amplitude too. That makes (a) false, since it says such a signal cannot have amplitude discontinuities, and also (b) false, which claims no phase discontinuities.
When one oscillator is used and only its frequency is changed (a voltage-controlled oscillator), the phase carries on from where it was, so the waveform is continuous: no discontinuity in amplitude or phase. That makes (d) true and (c) false.
Every option other than (d) only contains (a), (b) or (c), which is why options A, B and D fail.
Post your comment
Please log in or register to post a comment.
Examination Categories
- SSC Exams
- Banking Exams
- Teaching Exams
- Civil Services Exams
- Railways Exams
- Engineering Recruitment Exams
- Defence Exams
- State Government Exams
- Police Exams
- Insurance Exams
- Nursing Exams
- Other Government Exams
- NRA CET
- PG Entrance Exams
- Campus Placement
- MBA Entrance Exams
- CUET and UG Entrance
- Judiciary Exams
- Regulatory Body Exams
- Software Development